I did some more disassembly today. I got the throttle cables disconnected, unhooked the exhaust crossover pipe from the manifolds (without breaking any of the studs), removed some more vacuum hoses and found a few more surprises.
First up, check out the how the the main throttle linkage was attached:
Also lurking behind the rear throttle body was this gem:
No vacuum leak through that screw!
As expected, I found a couple of vacuum lines that were hard, brittle and cracked and a few with breaks in them -- which explains why the car ran inconsistently.
Right now -- I think I'm down to taking out the flex plate, bell housing and motor mount bolts to free the motor.